It is desirable in certain situation to control objects without physically contacting them. For example, it may be desirable to control the position, orientation, or configuration of living cells. Such control would be useful in a variety of clinical, diagnostic, and therapeutic uses, such as wound healing, tissue generation, and treatment and/or prevention of neurodegenerative disease and metastasis.
Various light-based methods have been proposed in the past to control dielectric objects. In one such method, the object is irradiated with highly-focused, high-intensity light so as to generate an electric field across the object having a strong intensity gradient. Once the electric field is established, the object is in effect trapped by the irradiated light and lateral movement of the apparatus that delivers the light results in corresponding lateral movement of the object. Although such a method may be used to control living cells, the high intensity of the light is undesirable given that it can damage or even kill the cells. Accordingly, it would be desirable to have an alternative mechanism for controlling a dielectric object, such as cells.